Apparatus for powder removal

ABSTRACT

An apparatus for removing excess, airborne powder following the application of a powder material to a moving surface such as a web or sheet wherein a manifold is positioned downstream of the powder application to entrap the airborne powder and the collected powder is removed by the combined action of a fluid stream to move the powder towards the ends of the manifold and a gentle vacuum adjacent the manifold ends to exhaust the powder to, for example, an exhaust trap, and methods for removing excess, airborne powder.

1151 3,680,528 1451 Aug, 1, 1972 United States Patent Sanders [54]APPARATUSFORPOWDERREMOVAL 2,515,223 7/1950Hollick.......................15/345X 2,757,635 8/1956Lipsius.........................

118/312 ...ll8/637 X [72] Inventor: Robert C. Sanders, Syracuse, N.Y.

[73] Assignee: Oxy-Dry 3,404,418 10/1968 Fantuzzo................3,434,416 3/1969 Testone....................

Sprayer Corporation, 118/639 X Chicago, 111. 3,451,376 6/1969 Obuchi eta]. 18/637 ..1 18/637 [22] Filed: April 1, 1970 [21] Appl. No.: 24,523Primary Examiner-Louis K. Rimrodt Att0meyWo1fe, Hubbard, Leydig, Voit &Osann Related US. Application Data [63] Continuation-impart of Ser. No.811,381, ABSTRACT An apparatus for removing excess, airborne March 28,1969, abandoned. powder following the application of a powder materialto a moving surface such as a web or sheet wherein a manifold ispositioned downstream of the powder aplication to entrap the airbornepowder and the collected powder is removed by the combined action of afluid stream to move the powder towards the ends of the manifold and agentle vacuum adjacent the manifold ends to exhaust the powder to, forexample, an exhaust trap, and methods for removing excess, airbornepowder.

0. 78 mmm 3 001 1 D3 1 20 05 W W S 1m92 T l 0 N mm E mr s M M mmfl u P cs 6 E WWW C T n A mm! m T mm k s uh e D mmm R E mmm T r v I n N L U C dS M U.| .F 11. 2 8 6 555 5 1.11 .1

13 Claims, 4 Drawing Figures 3,287,755 11/1966Pansini............................15/17 1,850,502 3/1932 l-iilker...l39/1C APPARATUS FOR POWDER REMOVAL This is a continuation-in-part ofcopending application Ser. No. 811,381, filed Mar. 28, 1969 nowabandoned.

, This invention relates to apparatus for removing airborne powder fromthe atmosphere and, more particularly to an apparatus that is used inconjunction with the application of a powder to a moving surface toremove the excess, airborne powder following the powder application.

In many industrial situations it is extremely desirable or necessary todeposit a powder material on a moving surface. As one representativeexample, in the printing industry, it is conventional to apply(generally electrostatically) a powder such as starch onto a moving webor sheet to prevent the smearing of ink. While this powder applicationeffectively prevents smearing, not all of the powder is adherred to thetravelling surface. A significant amount remains airborne and eventuallycollects on the equipment, the walls, ceiling and floor of the pressroom and even on the individuals in the area.

Where a sheet-fed press is involved, separate gripper bars carryindividual sheets and there is a gap between the end of one sheet andthe forward end of the next sheet. This causes an intermittent pulsatingof the powder which increases the tendency of the powder to stayairborne. This excess powder is often termed fly around.

In a web-fed press, other problems can arise. Thus, powder applicatorsare generally equipped to dispense the powder over a set distance. And,when a web with a width narrower than that set distance is to havepowder deposited thereupon, not only will the air turbulence caused bythe moving web cause excess powder to remain airborne but also some ofthe powder dispensed in areas where there is no moving web below willfall by gravity past the web.

Considerable effort has in the past been directed towards developingapparatus suitable for collecting most or all of this excess powder.Such apparatus have generally involved enclosing the whole area in whichthe powder was applied and then employing vacuum to transport the powderfrom adjacent the sheet. Typically, these solutions have provedexpensive, have af fected the quality of the powder application itselfand installation on the presses have sometimes been difficult because ofthe available space in the press for installation.

It is accordingly a primary aim of the present invention to provide amethod and apparatus for removing excess, airborne powder from a movingsurface following the application of powder to that surface which iseconomical and can remove a significant amount of the excess powderwithout significantly affecting the desired application of the powder tothe sheet.

Another object of the present invention is to provide an apparatus whichis sufficiently compact so that it may be easily mounted on mostconventional printing presses.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds, taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a perspective view of one embodiment of the apparatus of thepresent invention and illustrating the positioning of the apparatus inrelation to the powder applicator, a portion of the manifold beingpartly broken away to illustrate the air or fluid distribution means;

FIG. 2 is a cross-sectional view taken along lines 2- 2 of FIG. 1 andillustrating in greater detail the cabinet for minimizing the escape ofany collected powder;

FIG. 3 is a cross-sectional view taken along lines 3- 3 of FIG. 1 andillustrating the positioning of the fluid distribution means in relationto the manifold; and

FIG. 4 is a cross-sectional view taken along lines 4- 4 of FIG. 3 andshowing in detail the fluid distribution means.

While the invention is susceptible of various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that it is not intended to limit theinvention to the particular forms disclosed, but, on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the scope and spirit of the invention.

Turning to the figures, FIGS. 1 and 2 illustrate an exemplary embodimentfor effecting the removal of airborne powder following the applicationof the powder to a moving surface without significantly affecting theeffectiveness of the powder application itself. As shown, powder 10 isapplied to a moving surface 12 by a powder sprayer or applicator 14. Anyconventional sprayer may be employed. Electrostatic powder sprayers,such as are illustrated and claimed in U.S. Pat. Nos. 3,273,016,3,292,045, 3,292,046, 3,341,740 and 3,344,312 may be advantageouslyemployed.

In accordance with one feature of the present invention, a collectingmeans is provided to entrap at least a significant portion of theairborne powder. As shown, a collecting surface or manifold 16 isprovided. The manifold may have any desired shape for the collectingsurface providing that it forms an open entrapping enclosure for thepowder. The enclosure should allow free ingress while restrictingegress. It is preferred to employ an enclosure with a collecting surfacethat is substantially rectangular in shape, the rectangle being open onthe bottom side adjacent the moving surface 12 to achieve optimumperformance. However, adequate performance, it is believed, can beprovided when the cross section of the surface constitutes othergeometrical shapes such as semicircular, parabolic and the like. In theillustrative embodiment, the manifold 16 may have rectangular collectingsurface 18 with a width w of 12 inches and a height of 3 inches.Desirably, the manifold should have a length which is substantiallyequivalent to the maximum side-to-side spray capability of the sprayeritself. Because of the turbulence caused by the high speed motion of thetravelling surfaces which will generally be involved, the excess powderparticles will concentrate into an area downstream from the powderapplicator. The exact positioning of the manifold will vary dependingupon the normal operating speed of the sheet or web that is beingsprayed. As an example, when used in connection with a sheet-fed pressoperating at conventional press speeds, it has generally been foundsuitable to position the manifold 16 about 6 to 8 inches downstream froman electrostatic powder sprayer.

To transport the entrapped powder particles from the enclosure orcollecting surface, another feature of the present invention providesthe combined action of a fluid such as air to direct the powderoutwardly towards the ends of the manifold and a gentle vacuum to pullthe powder from adjacent the manifold ends and exhaust the powderwithout pulling powder away from the sprayed moving surface. It is thecombination of these forces that provides successful powder removalwithout also pulling deposited powder off the moving sheet or web. Thus,the air or other fluid pressure must be sufficient to move the powderoutwardly to the manifold ends but not so great that the air stream ineffect, begins to function as a vacuum thereby pulling powder away fromthe sprayed surface. Similarly, the vacuum must be sufficiently gentleto prevent pulling powder away from the sprayed surface while stillbeing sufficient to maintain the movement of the powder particlestowards their ultimate collection in an exhaust trap, dispersion intothe atmosphere or connection with other exhaust systems. Thus, as isshown, air from a source not shown is passed through an air regulatorand filter 20 into lines 22 and 24 and through a fluid distribution tee26 which is located adjacent the center of manifold 16. The distributiontee 26 has orifices 28, 28 that direct the air or other fluid outward.Desirably, the distribution tee should be substantially in the center ofthey manifold so that the air pressure will push the particles towardsthe manifold ends with substantially the same force in both directions.Additionally, it has been found preferable to position the distributiontee close to the top of the interior collecting surface 18 of themanifold in such a manner that the orifices 28, 28' direct the air orother fluid toward surface 18. Optimum performance is achieved when theair flow contacts the collecting surface adjacent the plenums. This canbe accomplished by positioning the orifices 28, 28' at angles to thehorizontal of about 1 to As a representative example in connection witha sheet-fed press, it has been found adequate if the fluid sourceprovides a pressure of from 3 to pounds per square inch gage withorifices of about one thirty-secondth inch diameter.

It should, however, be appreciated that the distribution tee could havemore than one orifice to direct the flow if this is found necessary ordesirable. Generally, if multiple orifices are used, they will beemployed to direct, at least initially, the air towards the sides of theenclosure rather than straight to the ends of the manifold.

To collect the powder particles that exit from the ends of the manifoldthere are provided exhaust plenums through which the vacuum is pulledand suitably dimensioned to allow all of the exiting powder drawn by thegentle vacuum to be collected en route to an exhaust trap. The exhaustplenums provide a means to converge and further concentrate the powderstream. To this end, and as is shown, exhaust plenums 30 are providedwhich have an entrance face 32 with a transverse dimension substantiallyequivalent to the width w of the manifold and a height also equivalentto the height h of the manifold. As shown, the plenums 30 are connectedtogether with the manifold 16 to provide a continuous system. This canbe accomplished by any conventional fastening means such as soldering.

While this minimizes the amount of powder escape, it should beappreciated that satisfactory operation will also result when themanifold and the plenums are not connected. The wedge-shaped plenumsconcentrate the powder stream which exits the plenums through an exit34'which may be circular in shape and have a diameter corresponding tothe height of plenum entrance face 32. Thus, the height and transversedimensions of the plenums may be varied if desired. Similarly, while itis desirable to position the plenums 30 at about the same level as themanifold 16, they may be higher or lower if necessary because of thespatial limitations of the equipment with which the subject invention isbeing employed. The relative height can be varied widely as long as thevacuum remains sufficient to pull the powder stream through the plenums.The same considerations are involved as regards the distance between themanifold ends and the plenum. In the case of a sheet-fed press, theexhaust plenums may, for example, be positioned just outside the path ofthe gripper bars.

In accordance with another aspect of the present invention, an aircurtain is utilized in connection with the manifold to minimize escapeof powder from the manifold. Thus, as is shown in FIG. 1, an air curtain29 comprises an air regulation tube 31 which is positioned adjacent theside of the manifold 16 which is away from the powder sprayer 14. Air,from a source not shown, is supplied to an air regulator 33 to the airregulation tube 31. The air can suitably exit from the air regulationtube by means of a series of spaced orifices. As an example, it has beenfound satisfactory to employ about 0.030 inch orifices spaced about 1inches apart. A pressure of about 2 to 6 pounds gage is suitable. Itshould be appreciated that adequate performance can be achieved withoutuse of the air curtain; but, to obtain optimum benefits from the presentinvention, the air curtain should be utilized.

The transporting of the powder particles from adjacent the ends of themanifold to the plenums and eventually into an exhaust trap is carriedout by providing a means for creating a gentle vacuum. As shown, ablower 36 creates a vacuum which moves the powder stream into theplenums 30, through flexible conduits 38, a T 40, conduit 42 and into anexhaust trap. The length of conduit between the entrance to thedistribution tee and each plenum should be substantially the same sothat an equal pressure arrangement will be provided. Unequal pressurewould result in escape of part of the powder particles.

When employed in conjunction with a system including the examples forthe various elements hereinbefore set forth, the flexible conduit maysuitably have an inside diameter of about 3 inches and the tee may havean outlet on the blower side of about 4 inches. Heavy duty applicationsmay require the employment of larger diameter conduits and T outlet. Theblower itself may suitably operate at a capacity of about 350 cubic feetper minute of air.

In accordance with a further feature of the present invention, thepowder particles may be collected in an exhaust trap which is air orfluid permeable to allow the air or fluid to pass therethrough. To thisend, the powder collects in an exhaust trap 44, which may suitably be awoven cotton bag that is sufiiciently porous to allow exhaust of the airinto the atmosphere. Desirably, the exhaust trap should have a capacitythat will be sufficient to minimize the frequency with which it must becleaned to remove the collected powder. As an example, a trap having a100 pound capacity could be employed. For optimum operation the powdershould not be allowed to occupy more than about 5 to percent of the areaof the trap itself. A 100 pound trap, used in connection with depositingstarch onto printed sheets in a sheet-fed press could perhaps beexpected to collect anywhere from about 2 to about 30 pounds per 120operating hours. If desired, the powder stream could be joined with anyexisting exhaust system or could also be vented to the atmosphere.

While the exhaust trap will collect the vast majority of the powder, asmall amount can be carried through the woven bag by the air passingtherethrough. Pursuant to still another feature of the presentinvention, an additional barrier to escape of powder into the air may beprovided by housing the exhaust trap in an enclosure provided with afiltered egress. Thus, a cabinet 46 is provided to house the exhausttrap 44. The cabinet may be formed with a removable top plate 48 and agasket 50. The top plate may be fastened to the top edge of the cabinetby any suitable means. An air tight coupling 52 is provided toaccommodate the conduit 42. A filter 54 is set in one side of thecabinet in a suitable frame and inregister with an exhaust or egress forthe air.

It should be appreciated that the use of a symmetrical system, ie fluiddistribution T 26 located in the middle of the manifold and equal lengthconduits, is preferred due to its simplicity. However, it is within thepresent invention to vary the respective conduit lengths and position ofthe tee to provide a system that coordinates the relative vacuum andfluid pressure to achieve removal of the powder. More specifically,within certain limits, the vacuum could be increased on one siderelative to the other side (by varying conduit length) and the tee movedcloser to the side of least vacuum to still provide for effectiveremoval.

In addition, when dealing with a web-fed press or other situations whenthe moving surface is not as wide as the set distance of the powderapplicator, it may be desirable to include a second manifold 56 anddistribution tee 58. This manifold may be positioned below the web ormoving surface with the collecting surface facing upwardly. Noadditional plenums are necessary.

Thus, as has been seen, the present invention provides a unique methodand apparatus for removing excess airborne powder following powderapplication to the surface of a sheet, web or other surface which istravelling at, generally, a high rate of speed. The collection andremoval of the powder is achieved without effecting the powderpreviously deposited upon the moving surface yet is compact and can beeasily mounted trib tion means located s 'd manif ld a d i te mediatethe ends to direct ii ui towardst eeniiso said manifold, a fluid sourcefor supplying fluid to said fluid distribution means to cause the powderto move towards the ends, a plenum located adjacent each end of saidmanifold and means to exhaust the powder from adjacent the ends of saidmanifold through said plenums as powder is moved adjacent the ends.

2. The apparatus of claim 1 which includes an exhaust means comprisingan exhaust trap to collect the powder while being sufficiently porous toallow fluid to pass therethrough and means coupling said plenums to saidexhaust trap.

3. The apparatus of claim 1 wherein an air curtain is positionedadjacent the side of the manifold downstream from the powderapplication.

4. The apparatus of claim 1 wherein the plenums and manifold areconnected together.

5. The apparatus of claim 1 wherein the fluid distribution means arepositioned adjacent the center of said manifold and the vacuum for eachend is substantially the same.

6. The apparatus of claim 1 wherein the fluid source is air.

7. The apparatus of claim 1 wherein the manifold has a rectangularcollection surface.

8. The apparatus of claim 1 wherein the manifold is located downstreamof the powder applicator.

9. The apparatus of claim 7 wherein the manifold is positioned above themoving surface a distance substantially equal to that of the powderapplicator.

10. The apparatus of claim 7 wherein a second manifold and fluiddistribution means are positioned below the moving surface to collectfalling powder and direct it towards said plenums.

11. The apparatus of claim 2 wherein the coupling means is flexibletubing and said vacuum means is positioned between said plenums and saidexhaust trap, the length of tubing from each of said plenums to saidvacuum means being substantially the same.

12. The apparatus of claim 10 wherein said vacuum means is a blower.

13. The apparatus of claim 2 wherein a closed compartment encloses saidexhaust trap, said compartment being provided with an opening and afilter in register therewith to contain the collected powder whileproviding an egress for the fluid.

1. An apparatus for removing excess, airborne powder following theapplication of the powder from an applicator to a moving surface whichcomprises a manifold having a pair of ends and positioned relative tothe moving surface and the powder application to entrap at least some ofthe airborne powder, fluid distribution means located in said manifoldand intermediate the ends to direct fluid towards the ends of saidmanifold, a fluid source for supplying fluid to said fluid distributionmeans to cause the powder to move towards the ends, a plenum locatedadjacent each end of said manifold and means to exhaust the powder fromadjacent the ends of said manifold through said plenums as powder ismoved adjacent the ends.
 2. The apparatus of claim 1 which includes anexhaust means comprising an exhaust trap to collect the powder whilebeing sufficiently porous to allow fluid to pass therethrough and meanscoupling said plenums to said exhaust trap.
 3. The apparatus of claim 1wherein an air curtain is positioned adjacent the side of the manifolddownstream from the powder application.
 4. The apparatus of claim 1wherein the plenums and manifold are connected together.
 5. Theapparatus of claim 1 wherein the fluid distribution means are positionedadjacent the center of said manifold and the vacuum for each end issubstantially the same.
 6. The apparatus of claim 1 wherein the fluidsource is air.
 7. The apparatus of claim 1 wherein the manifold has arectangular collection surface.
 8. The apparatus of claim 1 wherein themanifold is located downstream of the powder applicator.
 9. Theapparatus of claim 7 wherein the manifold is positioned above the movingsurface a distance substantially equal to that of the powder applicator.10. The apparatus of claim 7 wherein a second manifold and fluiddistribution means are positioned below the moving surface to collectfalling powder and direct it towards said plenums.
 11. The apparatus ofclaim 2 wherein the coupling means is flexible tubing and said vacuummeans is positioned between said plenums and said exhaust trap, thelength of tubing from each of said plenums to said vacuum means bEingsubstantially the same.
 12. The apparatus of claim 10 wherein saidvacuum means is a blower.
 13. The apparatus of claim 2 wherein a closedcompartment encloses said exhaust trap, said compartment being providedwith an opening and a filter in register therewith to contain thecollected powder while providing an egress for the fluid.